<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div,p,.demo{
            width: 150px;
            height: 150px;
            float: left;
            margin: 20px;
            border: 1px solid #ccc;
        }
    </style>
</head>
<body>
    <div id="box">hello</div>
    <p>world</p>
    <div class="demo">我想啊哈哈哦学习</div>
</body>
</html>
<script src="js/jquery-1.10.1.js"></script>
<script>
    $(function () {
        //通过jquery获取群组选择器
        $("#box,p,.demo").css("background","yellow");
    })
</script>